Excision Repair Affects the Specificity of UV Mutagenesis in the lacI+ Gene of Escherichia coli: Possible Involvement of Secondary DNA Structure
Using a system which allows the determination of 72 base pair changes in the lacI + gene of Escherichia coli carried on an F' plasmid, it was found that the distribution of UV-induced mutations occurring in a ΔUvrB strain was only different at one particular site when compared to the wild-type strain. It is proposed that secondary DNA structure is important in the UV-induction of mutation, which is discussed with reference to the formation of modified tRNA genes: nonsense suppressors. Furthermore, the mutational spectrum obtained at low UV fluence in the ΔUvrB strain was significantly different from that at high UV fluence.
KeywordsExcision Repair Mutational Spectrum Pyrimidine Dimer Base Pair Change Nonsense Suppressor
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